Manufacture of paper-board.



L. W. CASE.

MANUFACTURE OF PAPER BOARD.

APPLIQTION FIILED use. a. 1913.

Patented June 13, 1916.

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LAWRENCE W. CASE, OF HIGHLAND PARK, CONNECTICUT.

MANUFACTURE OF PAPER-BOARD.

Application filed December 8,1913.

To all whom it may concern:

Be it known that I, LAWRENCE W. CASE, a citizen of the United States, residing at Highland Park, in the county of Hartford and State of Connecticut, have invented a new anduseful Improvement in the Manufacture of Paper-Board, of which the following is a specification.

This invention relates to the manufacture of Very thick and heavy board from sheets or webs of paper, such material, for instance, as is used for electrical insulating purposes.

The object of the invention is to provide a simple process and apparatus by means of which thick, dense, and heavy board suitable for electrical insulating and like pur poses can be produced easily and inexpensively from sheets 01' webs of paper.

In carrying out this process, sheets or continuous webs of strong paper are first treated or coated on one surface with an adhesive compound. After this adhesive has become set a number of these sheets or continuous webs are fed together, superposed, between heavy calendering or pressing cylinders, but just before entering between such cylinders the surface of the sheets or webs which are coated with dried adhesive, are so treated that the adhesive is softened to the necessary degree to insure that the sheets or webs will firmly adhere and form a dense substantial board when pressed together by the I cylinders.

Figure 1 of the accompanying drawings shows a side elevation, with parts broken away, of a machine for feeding, moistening and uniting a number of continuous webs of paper which have previously been treated with adhesive. Fig. 2 shows a side elevation of a portion of the feed and spray pipes provided for softening the adhesive on the sheets. Fig. 3 shows a plan of the adhesive softening pipes.

The machine illustrated has 1. pright frames 1 upon which are supported nine rolls of paper 2, although of course, the invention is not limited to this precise number of rolls. These rolls of paper are carried on shafts?) which are .held by bearings 4 attached to the frames. The shafts are shown as having pulleys 5 provided withfriction brakes 6, the tension of which can be regu lated' so that the rolls will unwind and the paper will feed with a uniform tension. The paper feeds from the rolls around bars 7 thatextend across the frames, and over and Specification of Letters Patent.

v ply pipe 23 passed through the Patented Julie 13, 1916. Serial No. 805,466.

under tiers of tubes or bars 8 and 9. From the latter bars the sheets or webs are led together between the calendering or pressing cylinders 10 which are supported in ournal pillows 11 mounted in frame 12. The upper cylinder bearings are provided with means, such as the screw 13, for imparting the requisite pressure to the paper as it passes between the cylinders. The shaft of the lower cylinder has a gear 14 wrtlrwhich meshes a pinion 15 on a shaft provided with a .driving pulley 16. The sheets or webs after passing between the pressing cyllnders, may pass between dampening rolls 17 and then be cut into sheets or, as shown, wound in a thathas a gear 19 which is engaged by a pin- 1011 20 on a shaft provided with a driving pulley 21. The calendering or pressure cyllnders may or may not be heated as is common in machines of this character.

Extending horizontally between the sheets or webs, in front of and adjacent to the presslng cylinders, are pipes 22 that are provided with small holes or slots. These pipes at one end are connected with a supand at the other end with an exhaust pipe 24, valves 25 being provided whereby any of the horizontal pipes may be shut off from the supply and exhaust pipes. The supply pipe is designed to be connected with a suitable source of supply of adhesive solvent, as-steam.

The continuous webs or sheets of paper to be made up into board, according to this process and by such a machine as herein described, are first coated on one side with an adhesive such as paste, glue or shellac. This is allowed to dry and after it has become set, the desired number of sheets or webs are machine illustrated. Just before the superposed plies of sheets or webs pass between the calendering or pressure cylinders, the surfaces which have been coated with the adhesive are subjected to a spray or vapor of steam, water or other solvent which will soften the adhesive, so that when the sheets or webs pass between the cylinders and are pressed together, they will be united and solified into a thick, dense, heavy board.

' In practising this process the sheets .or webs are coated or treated with adhesive and the adhesive is allowed to dry and set before they are passed through the uniting machine. As it is unnecessary to manipulate roll upon a shaft 18 sheets or webs carrying soft, sticky or gummy adhesive, themachine for carrying out the process does not become gummed and consequently it operates more uniformly,

accurately and efiiciently than it otherwise would, if required to-handle sheets or webs with soft adhesive. Furthermore, the sheets or webs prepared in this manner can be more neatly, evenly and thoroughly coated and impregnated with adhesive than if the adhesive were sprayed upon them just before they pass between the pressure cyl1nders'. With this process any number of sheets or Webs can be built up into a solid board so as to obtain the required thickness and desired density, and the adhesive can be softened to just the required amount to insure the thorough adhesion of the various plies, for the solvent which is sprayed upon the sheets or webs for softening the adhesive y can be exactly regulated.

The invention'claim'ed'isz' 1 The method of forming insulating board for electrical purposes which consists in coating the entire surface of one side of each of a plural number of long sheets of unglazed paper with an adhesive compound and allowing said compound to become set. feeding said sheets of coated paper continuously and successively superposing them upon each other, rendering the set adhesive compound adherescent just prior to the apposition ofthe surfaces of the sheets "coming into contact, and immediately subjecting said superposed sheets with the adherescent adhesive to a rolling pressure and thus uniting them into an integral structure.

2. The method of forming insulating board for electrical purposes which consists in coating the entire surface of one side of each of a plural number of long sheets of unglazed paper with a liquid adhesive compound and allowing said compound to permeate the paper and become dry, feeding said sheets of coated paper continuously and successively superposl-ng them upon each other, moistening and rendering adherescent the dry adhesive compound with a solvent 

